Electronic devices are widely used in many types of electronic equipment. Such electronic devices are often grouped together and packaged in a single electronic module. A typical electronic module may include one or more integrated circuits (ICs), such as microprocessors, etc., as well as other discreet components (e.g., resistors, capacitors, etc.) mounted on a substrate, for example. One common material used for making such substrates are low temperature co-fired ceramics (LTCC), for example.
Discreet components may account for 80% or more of the total parts in a given electrical circuit design. While the physical size of the discrete components may be relatively small, the footprint required for their placement may be 2 to 3 times their actual size. This represents a significant portion of the available surface area of the substrate. Continuing demands for higher density packaging and miniaturization trends often require that the available surface area on a substrate be utilized by the most significant parts, such as ICs, for example.
The density limitations of current packaging technology are rapidly being reached. As a result, attempts are being made to incorporate discreet components within the substrate, rather than simply on the surface of the substrate. Yet, it may be difficult to embed discrete components within conventional LTCC materials due to a lack of available dielectric materials with higher dielectric values that are compatible with the substrate, with each other, and with the various metals used in the electronic module.
U.S. Pat. No. 6,191,934 to Liberatore et al. entitled “High Dielectric Constant Embedded Capacitors” discloses a capacitor that may be embedded within a multilayer ceramic circuit board. The capacitor is made using a capacitor ink formulation which provides a dielectric constant in a range of about 2600 to 4500, depending upon the size of the capacitor. The capacitor inks can be screen printed onto a glass-based green tape, or cast as a green tape layer. Electrodes may also be screen printed over and under the capacitor layer or green tape layer.
One limitation of such prior art capacitors is that it may be difficult to route signals near the capacitors because of the high constant dielectric materials used therein. This problem may become particularly acute when numerous capacitive structures are used, potentially resulting in insufficient space for routing the necessary signals.